"My Fiancée's" Miata: Part 9 - V8 Roadsters Cowl Stabilizer Braces, Sway Bar End Links and Track Test

by Daniel O'Donnell


Last winter, I was debating all the areas of improvement the Miata needed and first and foremost was chassis rigidity. The car crashes over bumps, the interior rattles and the cowl shakes like an old man’s fist when the neighbor kids are playing ball too close to his roses. It was getting to me and really needed to be the focus for improvement before future modifications could be made. Much like a relationship, a chassis needs to be rock solid for the whole package to work. My fiancée will appreciate that part.


Only the best FEA software applies when it comes to planning chassis reinforcement on the Miata. The open top nature of this car, along with 20 years of abuse from mother nature, have created a floppy chassis. The rear third is well supported by the roll bar, but the front 2/3rds needs some help. If only a company designed a really good chassis brace that would match the blue dotted line in my drawing...

I started doing mental gymnastics of the shortcomings of the chassis design of the Miata and quickly headed to the best design software money doesn’t have to buy, MS Paint. Looking at the chassis, the biggest area for improvement would be to connect the top of the window frame to the Blackbird roll bar, more or less making a coupe, but that’s not safely happening in a street car. I get enough grief about the roll bar clearance to my head already, I thought I better not add another bar in there to piss off more of our readers. If we imagine how forces are transmitted through the chassis, we can see that the roll bar does a good job tying in the rear chassis, but there was nothing up front to counteract the front suspension forces. Enter stage right, V8 Roadsters Cowl Stabilizer Braces.


V8 Roadsters Cowl Stabilizer Braces are a work of art and engineering. In this humble author's opinion, they are far and away the best design on the market for Miata's. Using sound engineering principles, V8 Roadsters brace connects the upper frame area, near the shock assembly mount, with the lower mounting bolts at the front of the door, one of the strongest areas of the Miata chassis.
Lovely details like this gusset help strengthen the main arm of the brace, while supporting for loads introduced perpendicularly to the bar via the arm that connects to the upper door mount.
This simple design helps transmit any movement efficiently to the main brace, as well as the chassis.
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Friday, December 29, 2017 9:23 AM
Did they ship the kit with those non plated, black bolts? Those thing will rust in about a second?
Saturday, December 30, 2017 7:27 AM
"When coming up to a corner, I wait until I feel like I am going to die, get on the brakes hard, turn, rest for 30 seconds on the next straight, then repeat."

LOL, I love that. Keep up the great work on this awesome car. I've often wondered about doing braces like this on my car! More inspiration to get to work.
Mike Kojima
Mike Kojimalink
Saturday, December 30, 2017 9:28 AM
I don't know what I think about the fender brace, no triangulation.
Saturday, December 30, 2017 11:24 AM
The triangular gussets between the perpendicular main elements should do a good job of adding stiffness.
Sunday, December 31, 2017 9:49 AM
Mike, on the topic of triangulation, isn’t the brace itself completing the triangle? On the fourth picture on page 2, the brace seems to be the third leg. In that picture, if the fender is the horizontal leg, and the cowl/firewall is the vertical leg, wouldn’t the brace be the third leg?

In the pictures of the OEM bracing on page 1, the braces themselves are straight (although one has parallel bends, and the other has chamfered holes). Is this brace on the Miata similar in that the straight line connects the fender and cowl/firewall, therefore stiffening the chassis?
Sunday, December 31, 2017 1:11 PM
Cowl stabilizers don't address the real problem which is the open space for the doors.
Wednesday, January 03, 2018 7:27 AM
This is the most effective way I've found to stiffen a miata or any convertible for that matter, besides a full cage. 3lbs of thinwall chromoly that takes about 5 minutes to bolt in. All the other style braces I've tried provided more of a placebo effect and testing reflected that. These are removable for street use.


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